Composites for antennas and other applications

ABSTRACT

Composite material, devices incorporating the composite material and methods of forming the composite material are provided. The composite material includes interstitial material that has at least one of a select relative permittivity property value and a select relative permeability property value. The composite material further includes inclusion material within the interstitial material. The inclusion material has at least one of a select relative permeability property value and a select relative permittivity property value. The select relative permeability and permittivity property values of the interstitial and the inclusion materials are selected so that the effective intrinsic impedance of the interstitial material and the inclusion material match the intrinsic impedance of air. Devices made from the composite include metamaterial and/or metamaterial-inspired (e.g., near-field LC-type parasitic) substrates and/or lenses, front-end protection, stealth absorbers, filters and mixers. Beyond the intrinsic, applications include miniature antennas and antenna arrays, directed energy weapons, EMI filters, RF and optical circuit components, among others.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/548,937, filed Aug. 27, 2009, now U.S. Pat. No. 8,723,722, issued May13, 2014, which claims priority to U.S. Provisional Patent ApplicationNo. 61/092,577, filed Aug. 28, 2008 and both having the same titleherewith, each of which is hereby incorporated herein in its entirety.

BACKGROUND

Electromagnetic waves, such as radio waves, incident on a boundarybetween two materials reflect or pass into each material based on thedifference in intrinsic impedance between the materials. For boundariesbetween air and high permittivity materials, a mismatch occurs thatresults in a loss of efficiency. This mismatch results in a reflectionof some of the incident energy. One application that implements highpermittivity materials is an antenna system. The use of highpermittivity materials in antenna systems provides benefits. Inparticular, with the use of high permittivity antenna systems, the sizeof the antenna can be reduced compared to typical antenna systems whichleads to greater applications and reduced overall sizes.

For the reasons stated above and for other reasons stated below, whichwill become apparent to those skilled in the art upon reading andunderstanding the present specification, there is a need in the art formaterials and devices containing materials that provide relatively highefficiency for electromagnetic waves at material boundaries.

SUMMARY

The above-mentioned problems of current systems are addressed byembodiments of the present invention and will be understood by readingand studying the following specification. The following summary is madeby way of example and not by way of limitation. It is merely provided toaid the reader in understanding some of the aspects of the invention.

In one embodiment, an antenna system is provided. The antenna systemincludes at least one antenna. The at least one antenna includesinterstitial material and inclusion material. The interstitial materialhas at least one of a select relative permittivity property value and aselect relative permeability property value. The inclusion material isreceived within the interstitial material. The inclusion material has atleast one of a select relative permeability property value and a selectrelative permittivity property value. The select relative permeabilityand permittivity property values of the interstitial material and theinclusion material provides an effective intrinsic impedance of thecomposite material that closely matches the intrinsic impedance of air.

In another embodiment, another antenna system is provided. The antennasystem includes at least one receive antenna and at least one transmitantenna. The at least one receive antenna includes interstitial materialthat has at least one of a select relative permittivity property valueand a select relative permeability property value. The inclusionmaterial is received within the interstitial material. The inclusionmaterial has at least one of a select relative permeability propertyvalue and a select relative permittivity property value. The selectrelative permeability and permittivity property values of theinterstitial material and the inclusion material provide an effectiveintrinsic impedance of the composite material that closely matches theintrinsic impedance of air. The at least one transmit antenna includesinterstitial material that has at least one of a select relativepermittivity property value and a select relative permeability propertyvalue. The inclusion material is received within the interstitialmaterial. The inclusion material has at least one of a select relativepermeability property value and a select relative permittivity propertyvalue. The select relative permeability and permittivity property valuesof the interstitial material and the inclusion material provide aneffective intrinsic impedance of the composite material that closelymatches the intrinsic impedance of air.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more easily understood and furtheradvantages and uses thereof more readily apparent, when considered inview of the detailed description and the following figures in which:

FIG. 1 is a three-dimensional illustration of composite material of oneembodiment of the present invention;

FIG. 2 is a three-dimensional illustration of composite material ofanother embodiment of the present invention;

FIG. 3 is a three-dimensional illustration of composite material of yetanother embodiment of the present invention;

FIG. 4 is a three-dimensional illustration of yet another compositematerial showing different shapes of inclusions;

FIG. 5A is a block diagram of a general antenna system of one embodimentof the present invention;

FIG. 5B is a front view of a radar system including antennas with acomposite material of one embodiment of the present invention;

FIG. 5C is a rear view of the radar system of FIG. 5B;

FIG. 6 is a top view of an antenna array of one embodiment of thepresent invention;

FIG. 7A is a block diagram of a system implementing antenna arrays ofone embodiment of the present invention;

FIG. 7B is a block diagram of a weapon system implementing antennaarrays of one embodiment of the present invention;

FIG. 7C is a block diagram of a directed energy weapon system of oneembodiment of the present invention;

FIG. 7D is a block diagram of a radar fuzing system of one embodiment ofthe present invention;

FIG. 8A is a block diagram of a system to tune composite material of oneembodiment of the present invention;

FIG. 8B is a block diagram of a mixer of one embodiment of the presentinvention;

FIG. 8C is a block diagram of a mixer formed in an antenna of oneembodiment of the present invention;

FIG. 8D is a block diagram of an antenna having both a mixer and afilter formed therein of one embodiment of the present invention;

FIG. 9 is a side cross-sectional view of stealth absorber material ofone embodiment of the present invention; and

FIG. 10 is a side view of a radome of one embodiment of the presentinvention.

In accordance with common practice, the various described features arenot drawn to scale but are drawn to emphasize specific features relevantto the present invention. Reference characters denote like elementsthroughout the figures and the specification.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof and in which is shown byway of illustration, specific embodiments in which the inventions may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that logical,mechanical and electrical changes may be made without departing from thespirit and scope of the present invention. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined only by the claims andequivalents thereof.

Embodiments of the present invention use metamaterials ormetamaterial-inspired elements at material boundaries. The metamaterialsand metamaterial-inspired elements are generally referred to ascomposite materials. Metamaterials are artificial materials that, inembodiments include interstitial material having inclusions. Theinterstitial material and the inclusions in embodiments each have atleast one of select relative permittivity property values and selectrelative permeability property values. Metamaterials have athree-dimensional periodic cellular architecture designed to produce aresponse to a specific excitation that would not be available innaturally occurring elements. In particular, metamaterials have unusualelectromagnetic properties that result in negative permittivity,negative permeability and/or negative index of refraction that arecontrolled by the design of the material. For example, standard mediawith a permeability of (μ)>0 and permittivity (∈)>0, refracts light ontothe opposite side of a surface normal at the boundary between thesurfaces in the customary manner. However, metamaterial with apermeability of (μ)<0 and permittivity (∈)<0, refracts light onto thesame side of normal at the boundary between the surfaces. By refractingan electromagnetic wave onto the same side of the surface normal, a muchstronger refraction event occurs than can be achieved by refractions inother natural materials.

Traditional metamaterial techniques generally refer to usingsub-wavelength sized resonators to achieve effective relativepermittivity (∈_(r))=effective relative permeability (μ_(r))=−1.Metamaterial-inspired techniques refer to the use of sub-wavelengthsized resonators to achieve relative permittivity (∈_(r)) other than −1and effective relative permeability (μ_(r)) other than −1. Formetamaterial inspired techniques, if one parameter is negative then theother is sometimes negative in order to prevent excessive losses.Metamaterial and metamaterial-inspired techniques both differ from usingthe natural permittivity and permeability of materials because bothtechniques utilize sub-wavelength sized resonators instead of theinherent material properties to achieve the effective materialproperties. In some embodiments of near-field lens applications aportion of the lens may be metamaterial, another portion may bemetamaterial-inspired and other portions may be natural materials,depending upon the characteristics of the source and the systemrequirements.

Some embodiments of composite material are made to have highpermittivity. Moreover, some embodiments provide composite materialswith effective intrinsic impedance that closely matches that of air. Theeffective intrinsic impedance that closely matches air is achieved inembodiments by making the relative permeability and permittivityproperties of the material relatively close in value (i.e., high-index).By matching the material to the intrinsic impedance of air, no wavereflection occurs at the material boundary with the air, which allowsmore energy to enter the material than would otherwise. Benefits ofcomposite material will be seen in embodiments as described below. Suchembodiments include antennas such as antennas having applications for,but not limited to, miniature phased and retrodirective arrays forfuzing applications, smaller antennas for medical implants,ground/building/car radars, magnetic resonance imaging (MRI) antennas,cell phones, two-way radios, trunked radio systems, undersea radar andcommunications, two-way trunking, commercial broadcast, radio frequencyidentification (RFID) systems, microscopy, smaller broadband printedcircuit boards (PCBs), cables, more effective anechoic chambers, missiledefense systems, etc. Other example embodiments include stealth coatingsto prevent detection by radar, spatial filters (e.g., EMI filters andfront-end protection) and mixers as discussed below. The composite alsoenables miniature near-field lenses and non-metamaterial(metamaterial-inspired) lenses, such as lenses described in the commonlyassigned U.S. patent application Ser. No. 11/955,795 filed Dec. 13,2007, now U.S. Pat. No. 7,928,900, which claims priority to U.S.Provisional Application No. 60/875,323 filed Dec. 15, 2006, titled“Improved Resolution Radar Using Metamaterials,” which are both hereinincorporated in their entirety.

Examples of composite materials 100, 200, 300 and 400 are illustrated inFIGS. 1, 2, 3 and 4, respectively. Referring to FIG. 1, compositematerial 100 of one embodiment is illustrated. The composite material100 includes interstitial material 102 that has a select relativepermittivity property value and inclusions 104 that have a selectrelative permeability property value. Examples of high permittivitymaterial used for the interstitial material include, but are not limitedto, D100 with an ∈_(r) of about 100, or X7R with ∈_(r)>1000 or TEFLON®.Examples of relatively high permeability material used for inclusionsinclude, but are not limited to, Z-phase Hexaferrites having∈_(r)=μ_(r)=12, G4256 with a μ_(r) of about 100, ferrite or othermaterials with μ_(r)>1000. In some embodiments, material with a naturalrelative high permittivity property value of 9 or greater is used andmaterial with a natural relative high permeability property value of 9or greater is used. A variety of manufacturing techniques may be used toassemble inclusions into interstitial material. For machinableinterstitial materials, space for the inclusions may be machined intothe interstitial material and the inclusions added as the composite isbuilt up one layer at a time. In some implementations, an injection moldcan be used to infuse the interstitial material between inclusionmaterials. In some implementations, the composite may be assembledstarting from the corners or in layers as the interstitial supports andinclusions are combined into the composite.

High permeability inclusions add significant complexity to the compositedesign because of their relatively high conductivity and because oflossy natural ferromagnetic resonances. By controlling the size ofinclusions, the shape of the inclusion, the concentration of inclusionsand by varying the composite filler types and morphology it is possibleto control frequency dispersion of complex permeability and permittivityof the composite material. It is also possible to reduce the size ofhigh permeability inclusions, while increasing their overall effect oncomposite permeability by spacing groups of inclusions closely toachieve dielectric enhancement.

As the embodiment of FIG. 1 illustrates, inclusions 104 have definedshapes of cylinders and half-cylinders. In FIG. 2, composite material200 is illustrated. Composite material 200 includes interstitialmaterial 202 and inclusions 204. In one embodiment, the interstitialmaterial 202 has a select relative permittivity property value and theinclusions 204 have a select relative permeability property value. Theshapes of the inclusions 204 are generally cross-shaped. Likewise, inFIG. 3, composite material 300 is illustrated. Composite material 300includes interstitial material 302 that has a select relativepermittivity property value and inclusions 304 that have a selectrelative permeability property value. The inclusions 304 of FIG. 3 arealso generally in a cross-shape that is formed with cylinders. Theindividual composite inclusions used in embodiments can be any shapeincluding, but not limited to, a cross 402, sphere 412, cylinder 404,cylinder forms 304, cone 406, hourglass 410, cube 408, arbitrary 414, orcombinations thereof. For example, FIG. 4 illustrates some possibleshapes of inclusions 402, 404, 406, 408, 410, 412 and 414 ininterstitial material 401 of composite material 400. It will beunderstood that different patterns of shapes can be arranged to achievea structure with desired characteristics. Moreover, the shapes of theinclusions control, in part, by losses by surface effects and element toelement effects. Hence, changing the shapes of the inclusions is alsoused to achieve a structure with desired characteristics in someembodiments.

As illustrated in FIGS. 1, 2 and 3, in some embodiments, the inclusions104, 204 and 304 are orientated in three-dimensions. For example,referring back to FIG. 3, an X-axis, a Y-axis, and a Z-axis areillustrated and how the inclusions 304 are orientated in relation to theX-, Y- and Z-axes. Having the inclusions orientated along thethree-dimensional axes controls anisotropy and dielectric enhancement.Further, in some embodiments, the inclusions 304 are located next toeach other in the interstitial material 302 so that they enhance atleast one of the permeability or permittivity of the composite material300 as discussed above. Although the composite material 100, 200, 300and 400 is illustrated in FIGS. 1, 2, 3 and 4 as having a generally acube shape, this is only for illustrative purposes. The compositematerial can have any shape needed for some applications (e.g., in az-phase hexaferrites embodiment).

In the embodiment discussed above in regard to FIGS. 1 through 4, theinterstitial material is described as having a select relativepermittivity property value and the inclusions as having a selectpermeability property value. However, in other embodiments theinterstitial material 202 has a select relative permeability propertyvalue and the inclusions 204 have a select relative permittivityproperty value. In further still other embodiments, both theinterstitial material 202 and the inclusion 204 have relatively highpermeability and relatively high permittivity property values.

As stated above, composite materials have many applications. Oneapplication involves the use of composite material in antennas. Examplesof antennas include, but are not limited to, microstrip/planar,frequency independent, wire, horn, dish, loop, slot, helical, etc. Anantenna is typically one of the largest elements of a radio because itmust be on the order of the size of the wavelength for good overallefficiency. By embedding an antenna in a composite of very highpermeability and very high permittivity material it is possible todramatically reduce the size of an antenna while preserving antennaefficiency. This opens new applications for antennas includingembodiments of miniature phased and retrodirective arrays for fuzingapplications, smaller antennas for medical implants, ground/building/carradars, MRI antennas, cell phones, two-way radios, trunked radiosystems, anechoic chambers, missile defense systems, etc., as discussedabove. With the use of composite material, the cost and size of theantennas will shrink dramatically. This will result in many new types ofproducts being brought to the market that previously could not bebrought to market because of their cost or size.

In one antenna embodiment, a composite with individual inclusionssmaller than half the wavelength of the incident radio wave is used.Also, the relative permeability and permittivity properties in thecomposite material of the antenna are selected close in value, whichcauses the effective intrinsic impedance of the material to closelymatch that of air. By matching the material to the intrinsic impedanceof air, little wave reflection occurs at the material boundary with air,which allows more energy into the antenna thereby increasing efficiency.An example of a device 500 of embodiments implementing antennas asdescribed above is illustrated in the block diagram of FIG. 5A. Asillustrated, this device 500 embodiment includes a transmit antenna 502and a receive antenna 504. At least the receive antenna 504 is made fromcomposite material, as discussed above, having relative permeability andpermittivity properties that are selected relatively close in value,which causes the effective intrinsic impedance of the material toclosely match that of air. In one embodiment, both the receive andtransmit antennas 504 and 502, respectively, are made from compositematerial as discussed above having relative permeability andpermittivity properties that are selected relatively close in value,which causes the effective intrinsic impedance of the material torelatively closely match that of air. The device 500 further includes anoperating circuit 506. Operating circuit 506 includes a receiver 510coupled to receive signals from the receive antenna 504 and transmitter508 coupled to transmit signals to the transmit antenna 502. Alsoincluded in the operating circuit 506, is a controller 512 andprocessing circuits 514. The controller controls operation of the device500. The processing circuits 514 process signals received by thereceiver 510. The device 500 of FIG. 5A could be any device including,but not limited to, a radar device, a medical implant device, an MRIdevice as well as communication devices including, but not limited to,cell phones, two-way radios, trunked radios, RFID tags, underseacommunication systems, anechoic chambers, missile defense systems,commercial broadcast systems, microscopy systems, smaller broadbandPCBs, etc.

Referring to FIG. 5B, an example of a radar module 520 including twoantennas 522 and 524 made of composite material of an embodiment isillustrated. In particular, FIGS. 5B and 5C illustrate front and backviews, respectively, of an integrated transmit/receive radar module 520of one embodiment. The radar module 520 includes the transmit antenna522 and the receive antenna 524. As stated above, the antennas 522 and524 are made from a composite material that includes interstitialmaterial having a select relative permittivity property value andmagnetic material (inclusions) having a select relative permeabilityproperty value. The select relative permeability and permittivityproperties values are selected so that the effective intrinsic impedanceof the interstitial and magnetic material matches the intrinsicimpedance of air. The back view of the radar module 520, as shown inFIG. 5C, illustrates that the radar module 520 in this embodimentincludes a low phase noise oscillator 526, an up converter 528, ahigh-power transmitter 530, a VCO/Frequency divider 532, a time delay534, a second down converter 536, low noise amplifier (LNA) receivers538, another second down converter 540 and frequency multipliers 542.

As further discussed above, the composite material can be used in alltypes of antenna and antenna arrays. For example, referring to FIG. 6,an example of an antenna array 600 is illustrated having a plurality ofresonators 602 made from the composite material, as discussed above.Resonators 602 of FIG. 6 are individual patch antennas. In oneembodiment, the composite material acts as lens that is positioned overthe antenna elements to direct energy to the elements. In further anembodiment, the resonators 602 are near-field resonators that are usedin a non-metamaterial way to focus antenna beams while achieving widebandwidths, wherein the permittivity equals the permeability. In thisembodiment, an electro-dielectric is used to focus an antenna.

In another embodiment of an antenna array 600, composite material wouldsurround antenna elements and act as parasitic and/or substrateelements. Antenna parasitic material elements are sometimes used in thedesign of directional antennas to focus antenna energy. However,traditional parasitic elements are also required to be on the order ofthe size of the radio wavelength to work effectively. Because of thesize restriction of antennas and antenna parasitic elements, it isdifficult to develop a directional antenna for miniature proximitysensors. Embodiments of composite material that act as parasiticelements are acted upon by electromagnetic waves similar to antennas andtraditional parasitic, but are much smaller because they resonate due toa built-in LC-like resonant structure as opposed to resonating due tothe spatial dimensions of the device used by antennas and traditionalparasitic. The LC-like parasitic elements can be much smaller thantraditional distributed-type parasitic resonators. Because the elementsare very small, many of them may be used per wavelength or antenna tofinely control and optimize antenna performance parameters such asbeamwidth. By designing the parasitic elements using a composite ofrelatively matched high permeability and high permittivity material itis possible to dramatically reduce antenna size while preserving antennaefficiency because the size of the wave is small in the high-indexmaterial, but the material is matched to free-space. The performance ofantennas that utilize high-index parasitic and possibly substrates willbe on-par with and often better than high-end antennas at a cost on-parwith presently available low-cost antennas.

Antenna arrays such as antenna array 600 have many applications. Anexample array system 700 is illustrated in FIG. 7A. In the example arraysystem 700, a transmitting array 704 and a receiving array 706 arerespectively coupled to a transmitter 708 and a receiver 710 of anoperation circuit 702. A control circuit 712 is in communication withthe transmitter 708 and the receiver 710. The transmitting array 704 andthe receiving array 706 in this embodiment are made of resonators ornon-resonant parasitic elements comprised of composite material havinginterstitial material having a select relative permittivity propertyvalue and material (inclusions) having a select relative permeabilityproperty value or a high-index inclusion in an interstitial material ofhigh or low permittivity. The select relative permeability andpermittivity property values are selected so that the effectiveintrinsic impedance of the interstitial material and inclusions matchthe intrinsic impedance of air. The array system 700 may be any type ofsystem that would benefit from the use of antenna arrays such as, butnot limited to, radar-based proximity sensors, such as fuzing/radarsystems, building/ground penetration systems, fire-control systems,missile defense systems, and the like. In some embodiments, widebandarray techniques known in the art are used to design antenna arrays tocompensate for bandwidth reductions that occur as a permittivity orpermeability increase.

In a proximity sensor embodiment, the array system 700 can be used topenetrate vegetation, soil, buildings, and metal with high resolution toidentify and track targets of interest. In some embodiments, thedielectric properties of the metamaterial or metamaterial-like (∈ vs. μ)are relatively matched to improve resolution. The composite providessub-wavelength resolution that enables proximity sensors to sense withhigh resolution small objects just below the surface, throughvegetation, within buildings, in cave openings, below water and insidemetal structures. Super resolution (Θ_(min)<<λ/2 beamwidth) improvesclutter rejection and improves dynamic range, which improves depth ofpenetration and interference rejection (e.g., reduces FM captureeffect). The narrow beamwidth reduces the likelihood of interference toother systems. Sub-wavelength techniques have so far achieved up toapproximately a 1000-fold improvement in resolution over the diffractionlimit with the limit controlled by losses instead of the wavelength. Topenetrate vegetation, soil, buildings, metal and water for narrow-bandradar utilizing sub-wavelength techniques, an operating frequency of theproximity sensor of approximately 300 MHz or less is used in oneembodiment. Below this frequency, soil attenuation is beginning todecrease and it is low enough in attenuation that significant materialpenetration can occur with reasonable transmit power levels. Anadditional benefit for proximity sensor ground and building penetrationapplications is that the reflection by water and soil is much lowerversus grazing angle of incidence for frequencies below 1 GHz anddecreases significantly with every 100 MHz of frequency reduction. Thisis important for depth of penetration and to improve the multipathenvironment. Metamaterials and metamaterial-inspired near-fieldparasitics can be used to focus antennas to much tighter beamwidths thanachievable using conventional diffraction limited techniques. This canbe used to implement narrow beamwidths on low-cost proximity sensors atlow radio frequencies, as stated above, as well as for ignoring clutterin ammunition fired at low inclination angles, to detect personneltargets and many other ways to improve proximity sensor performance. Inone embodiment, sub-wavelength illumination and sub-wavelength imagingare incorporated into the ground penetrating radar 700 to make itpossible to discern details within objects such as automobiles andarmored vehicles to optimize an attack point.

In one embodiment, simple height of burst (HOB) sensors include low-costtarget sensing systems and imaging seeker system implemented antennasystems with composite material, as discussed above, to enhance thecapabilities of weapon systems. An example of a weapon system 714 isillustrated in FIG. 7B. In FIG. 7B, the weapon system 714 is illustratedas having a controller 715, an HOB sensor 716 and an antenna 717. HOBsensor 716 may include a target sensor 718 and an image seeker 719. Asstated above, the antenna 717 is made from composite material asdiscussed above. Although FIG. 7B illustrates the use of one antenna717, more than one antenna could be used. The use of the compositematerial in the antenna 717 further provides protection against RFjammers. Typically, a circuit based on a semiconductor junction is usedon RF front-ends to protect from unintentional and intentionalhigh-power RF jammers. Because magnetic materials are used in theantenna composite, high-level interference will cause the magneticmaterial to saturate. Magnetic saturation of the front-end willattenuate the undesired and desired signal, but will handle much higherinterference power as compared to semiconductor protection because thejammer power is dissipated across the 3D antenna structure instead ofacross a 2D semiconductor junction. Because the antenna performanceitself degrades under jam, very little of the products of the nonlinearmixing action that occurs due to saturation effects are re-radiated ascompared to the diode approach. This prevents the jammer from detectingspurious signals created at the proximity sensor by the jammer. Theprimary effect of magnetic saturation is to attenuate the incomingsignals. For proximity sensors operating with a wide linear dynamicrange and strong signal-to-noise ratio under nominal conditions it ispossible for the proximity sensor to detect the desired signal whilebeing jammed with high-power interference. The new composite will enablea dramatic improvement in frontend protection and jam resistance overcurrent generation proximity sensors.

Another type of weapon system that implements composite material is adirected energy weapon system 750 illustrated in FIG. 7C. In thisembodiment, a lens 754 composed of composite material is used to directenergy 760 to a desired location. This energy weapon system 750 includeda support 751 that positions the lens 750 to direct the energy 760 to adesired location. The support 751, in this embodiment, is coupled to avehicle 752. A controller 758 controls an energy generator 756 toselectively generate the energy 760 directed by the lens 750. As statedabove, the lens 750 is made from composite material. In particular, thecomposite material in an embodiment includes interstitial material andinclusion material having select relative permeability and permittivityproperty values such that the effective intrinsic impedance of thecomposite material matches the intrinsic impedance of air. Theembodiment of the energy weapon system 750 mounted to a vehicle can beused for defeating/destroying IEDs, and the like. In anotherapplication, the energy weapon system 750 is used as a missile defensesystem to defeat/destroy incoming missiles, and the like. The missiledefense energy weapon system 750 may be stationary or mobile. A mobilemissile defense energy weapon system 750 is mounted on a vehicle suchas, but not limited to, a truck, plane, ship or train. In oneembodiment, the energy 760 generated by the energy generator 756 iselectromagnetic.

In some applications using lenses, it will be necessary to adjust theproperties of lens elements dynamically without saturation as thenear-field changes with time. All antennas generate near-fields that arevery complicated and change dramatically with time. For some near-fieldlens applications, it may not be possible to achieve the desired focalpoint or other features with lens elements exhibiting constant effectivedielectric properties. This is particularly true as the environment of alens changes and as the near-field penetrates various materials withinthe environment. Changing the effective material properties tocompensate for changes in the near-field of the source antenna issimilar to using antenna array techniques in that different elements ofthe array are stimulated differently, but in the case of antenna arraysthe inventors are stimulating the source elements differently, not theindividual lens elements. Antenna array theory also is mostly concernedwith the far-field, whereas near-field lens tuning is concerned withadapting the lens elements to compensate for local changes in thenear-field. In some embodiments, each lens element in a lens, such aslens 754 is subject to a magnetic and/or electric field of a givenstrength to dynamically adjust the property of the lens element. Anexample of the application of a field is illustrated generally in FIG.8A. In FIG. 8A (further discussed below) a field generator 806 applies afield 804 across composite material 802 which in this embodiment is alens element 802.

An example of a radar fuzing system 720 implementing an array system ofan embodiment is illustrated in the block diagram of FIG. 7D. Radarfuzing systems are generally used to determine valid signal returns frominvalid signal returns. The use of antenna arrays 722 and 724 of thisembodiment provides benefits over other types of antenna systemsincluding, but not limited to, the benefit of enabling miniaturelow-cost arrays for monostatic, hi-static, forward scatter/shadow,frequency stepped, Ultra-Wideband, multiple-input and multiple-output(MIMO) radar fuzing capabilities. The transmit antenna array 722 and thereceive antenna array 724 in this embodiment are made of resonatorscomprised of composite material having interstitial material having aselect relative permittivity property value and magnetic material(inclusions) having a select relative permeability property value orvice versa. The select relative permeability and permittivity propertiesvalues are selected so that the effective intrinsic impedance of theinterstitial and magnetic material approximately matches the intrinsicimpedance of air. In this embodiment, a modulator 734 applies a selectmodulation to transmitter 732. In response to the modulation, thetransmitter 732 transmits one or more transmit signals to a coupler 730.The coupler 730 passes the transmit signals to the transmit antennaarray 722 and receiver 736. Signals received by receiver 736 via thereceive antenna array 724 are processed and compared against the signalsfrom the coupler 730. The receiver 736 then outputs the comparison tothe decision circuit 744 for analysis. The decision circuit 744 thendetermines whether or not the return signal is a valid signal. Once adetermination of a valid or non-valid signal is determined, anappropriate output is then provided by the decision circuit 744.Embodiments of the radar fuzes have enhanced phase and retrodirectivecapability due to miniaturized phased array radar antennas and phasedarray antennas that can be used on a small projectile.

In further embodiments, voltage, current or externally applied electricor magnetic fields, are used on the composite material to tune thecomposite material for a desired application. In some embodiments, theexternal electrical or magnetic fields applied to the compositematerials are varied or turned on and off. FIG. 8A illustrates anexample of a device 800 with such a system. In FIG. 8A compositematerial 802, such as the composite material discussed above, is subjectto a field such as a magnetic field 804 generated between plates 808Aand 808B by field generator 806. An example embodiment that implementscomposite material that can be tuned is a mixer. By turning a magneticfield on and off, the composite material can be used as a mixer. Mixingoccurs by alternately magnetically saturating or detuning (i.e., turningoff) and removing the saturation/tuning in (i.e., turning on). Usingmagnetic saturation limits the range of frequencies at which thetechnique can be applied; however, a non-magnetic metamaterial tuningmixer allows a broad range of frequencies to optical and higher.Metamaterials are effectively nonlinear circuits that use resonance tocontrol effective material properties. By changing local oscillatorfrequency or amplitude, a mixer can be designed to implement the mixerby changing the nonlinear characteristics of a metamaterial so itbehaves like a diode-based mixer. An example mixer 820 is illustrated inFIG. 8B. In this example, a radio frequency (RF) is combined with alocal oscillator (LO) frequency to produce an intermediate frequency(IF). Hence, you can achieve a desired output (such as the IF of FIG.8B) by adjusting one of the frequencies of the inputs (RF or LO). In oneembodiment, a magnetic field strength applied to the mixer 820 isselectively varied to change the physical permeability. This changes theresonant frequency, which in turn changes the effective permeability andeffective permittivity of the mixer 820. In another embodiment, usingthe composite material 832 for an antenna 830, a mixer 834 is formed inthe antenna 830 itself with the benefits as discussed above. Thisembodiment is illustrated in FIG. 8C. Combining the mixer 834 with theantenna 830 provides an opportunity for improved noise performance.

In a similar manner, front-end adaptive filters embodiments are designedto be tuned using the composite metamaterial. By tapering the materialproperties and/or including loss into the composite, eitherintentionally or inherently, the composite can be used forelectromagnetic interference (EMI) protection or stealth material and tomatch to another material. Protecting from EMI using a composite regionis more effective than a protection diode because a much largerprotection region compared to a diode junction is provided using acomposite, which allows protection to higher power levels. In oneembodiment, at least one filter 844 is formed in the antenna 840. Inanother embodiment, illustrated in FIG. 8D, at least one filter 844 andat least one mixer 846 are formed in an antenna of the compositematerial 842. By implementing filters and mixing into the antennasubstrate, noise performance is improved by moving filtering anddown-conversion as close as possible to the antenna. High-indexcomposites may act as dielectric antennas whether an antenna is embeddedin the material or not. The thickness of the material is such that it ison the order of at least one wavelength (in the composite) in order toshrink the size of antennas dramatically, while maintaining efficiencyand minimizing reflections at the antenna surface.

Another example of an embodiment is illustrated in FIG. 9. In FIG. 9,stealth absorber material 900 (RF absorber) is formed from the compositematerial. In this example, composite material 902 is located at anair/material boundary 901. The composite material 902 includesinterstitial material in one example embodiment having a select relativepermittivity property value and a plurality of permeability inclusionsreceived in the interstitial material or vice versa. That is, in anotherexample embodiment, the interstitial material may have a select relativepermeability value and the inclusions may have a select relativepermittivity value. Regarding the first example embodiment, the selectrelative permittivity property value of the interstitial material andselect permeability property values of the permeability inclusions areselected so that the effective intrinsic impedance of the interstitialmaterial and the permeability inclusions match the intrinsic impedanceof air. Hence, a radar signal 906 is not reflected at the air/materialboundary 901 but is absorbed into the composite material 902, asillustrated. In one embodiment, anisotropic composite material is used.With the anisotropic material, the absorption or reflection behavesdifferently depending upon which axis the radio wave is incident. Forexample, in FIG. 9, the radio wave 906 is first incident on theair/material boundary 901 at generally a perpendicular angle. Because ofthis angle, the radio wave 906 is received in the composite material902. As further illustrated, the radio wave 906 is retained in thematerial 902 when the angle of incident is not generally perpendicularto a material boundary. In another embodiment, the metamaterials orresonant near-field composites are selected that have a permeabilitythat approaches infinity and a permeability that also approachesinfinity. In this embodiment, the wave speed is slowed so it effectivelystops the incident wave. Examples of items that could implement thestealth absorbing material as a coating include, but are not limited to,missiles, aircraft, boats, anechoic chambers, etc. The stealth material900 is also used in embodiments as an EMI protection for electroniccircuits and the like.

FIG. 10 further provides another embodiment. FIG. 10 illustrates a sideview of a radome 1000 of an embodiment. Radomes have a multitude ofdifferent shapes so embodiments are not limited by shape. The functionof a radome 1000 is to protect a lens or radar from outside weatherenvironments. In some embodiments, the composite material is used as aradome. In these embodiments, the composite material functions as atraditional radome to protect a lens, radar or other equipment fromenvironmental conditions as well as functions as described in the abovevarious embodiments (i.e., including, but not limited to, near-fieldparasitic, lenses, stealth material, antennas, mixers, filters, etc.).

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement, which is calculated to achieve the same purpose,may be substituted for the specific embodiment shown. This applicationis intended to cover any adaptations or variations of the presentinvention. Therefore, it is manifestly intended that this invention belimited only by the claims and the equivalents thereof.

The invention claimed is:
 1. An antenna system comprising: at least oneantenna comprising a composite material, the composite material of theat least one antenna comprising: interstitial material having at leastone of a select relative permittivity value or a select relativepermeability value; and inclusion material received within theinterstitial material, the inclusion material having at least the otherone of a select relative permeability value or a select relativepermittivity value, the select relative permeability and permittivityvalues of the interstitial material and the inclusion material providingan effective intrinsic impedance of the composite material that closelymatches an intrinsic impedance of air.
 2. The antenna system of claim 1,wherein the at least one antenna is at least one receive antenna, andwherein the antenna system further comprises: a receiver coupled toreceive signals from the at least one receive antenna; a processingcircuit to process signals from the receiver; and a controller tocontrol operations of the processing circuit.
 3. The antenna system ofclaim 2, further comprising: at least one transmit antenna; and atransmitter coupled to the at least one transmit antenna to transmitsignals out of the at least one transmit antenna, the controller coupledto the transmitter to control the operations of the transmitter.
 4. Theantenna system of claim 1, wherein the at least one antenna comprises atleast one receive antenna, and wherein the antenna system furthercomprises at least one transmit antenna, wherein the at least onereceive antenna and the at least one transmit antenna are part of aradar module.
 5. The antenna system of claim 1, wherein the at least oneantenna is at least one antenna array.
 6. The antenna system of claim 5,wherein the at least one antenna array further comprises: a transmittingarray, and a receiving array; and wherein the antenna system furthercomprises: a transmitter in communication with the transmitting array; areceiver in communication with the receiving array; and a controlcircuit in communication with the transmitter and the receiver.
 7. Theantenna system of claim 6, further comprising: a modulator configured toapply a select amount of modulation to the transmitter; and a couplerconfigured to pass transmit signals to the transmitting array and thereceiver, wherein the control circuit is a decision circuit configuredto determine whether a signal is a valid return signal.
 8. The antennasystem of claim 1, further comprising: a height of burst sensor incommunication with the at least one antenna; and a controller incommunication with the height of burst sensor.
 9. The antenna system ofclaim 8, wherein the height of burst sensor further comprises: a targetsensor; and an image sensor.
 10. The antenna system of claim 1, furthercomprising: at least one filter formed in the at least one antenna. 11.The antenna system of claim 1, further comprising: at least one mixerformed in the at least one antenna.
 12. The antenna system of claim 1,wherein the select relative permeability value and the select relativepermittivity value of at least one of the interstitial material or theinclusion material are close in value.
 13. The antenna system of claim1, wherein the inclusion material is orientated along three-dimensionalaxes to control anisotropy and dielectric enhancement.
 14. The antennasystem of claim 1, wherein positioning of the inclusion material withinthe interstitial material enhances at least one of the permeability orthe permittivity of the composite material.
 15. The antenna system ofclaim 1, wherein the inclusion material includes a plurality ofinclusions with at least one inclusion having a shape selected from thegroup of shapes consisting of cross, sphere, cone, cylinder, cylinderforms, hourglass, cube, and a curved surface.
 16. The antenna system ofclaim 1, wherein the select relative permittivity value and the selectrelative permeability value of at least one of the interstitial materialor the inclusion material is configured to change by the application ofat least one of a magnetic or an electric field on the compositematerial.
 17. An antenna system comprising: at least one receiveantenna, the at least one receive antenna including a composite materialcomprising: interstitial material having a permittivity value and apermeability value; and inclusion material received within theinterstitial material, the inclusion material having a permeabilityvalue and a permittivity value, the permeability value and thepermittivity value of the interstitial material and the permeabilityvalue and the permittivity value of the inclusion material providing aneffective intrinsic impedance of the composite material of the at leastone receive antenna that closely matches an intrinsic impedance of air;and at least one transmit antenna, the at least one transmit antennaincluding a composite material comprising: interstitial material havinga permittivity value and a permeability value; and inclusion materialreceived within the interstitial material, the inclusion material havinga permeability value and a permittivity value, the permeability valueand the permittivity value of the interstitial material and thepermeability value and the permittivity value of the inclusion materialproviding an effective intrinsic impedance of the composite material ofthe at least one transmit antenna that closely matches the intrinsicimpedance of air.
 18. The antenna system of claim 17, furthercomprising: a receiver coupled to receive signals from the at least onereceive antenna; and a transmitter coupled to transmit signals out ofthe at least one transmit antenna.
 19. The antenna system of claim 18,further comprising: a controller to control operations of thetransmitter.
 20. The antenna system of claim 17, wherein the at leastone receive antenna is a receiving antenna array and the at least onetransmit antenna is a transmitting antenna array.
 21. An antenna systemcomprising at least one antenna comprising a composite material, thecomposite material of the at least one antenna comprising: interstitialmaterial; and inclusion material in the interstitial material, apermeability value and a permittivity value of the interstitial materialand a permeability value and a permittivity value of the inclusionmaterial providing an effective intrinsic impedance of the compositematerial that closely matches an intrinsic impedance of air.